Our 2003 Cavalier is knocking under the dash when the heater/ac is on. What could that be?

eric_corbin

Seems like it is right under the glove box. Was told at auto zone that it might be a relay, but didn't know of one under the dash like that and they said it had to go bad before you could replace it> Doesn't seem right to me. Any help is appreciated

sidetrack85

Ya there is a relay under the glove box behind the kick panel. It is for the fresh air/ Re circulated air. Feel around under there (you will feel it clicking) and just unplug the harness. If you really want it fixed the part is about $40 and requires about 25% of the dash to be removed